A while back, I un-subscribed to this thread, as I saw it was becoming another typical crap-fest.
The nit-picking, arguing, and obsessing over trivial nothings doesn't keep me entertained.
Oh well, back out.... have at it.
Stuffed with popcorn.
It would be interesting to see the different caps and their frequency phase shift over the frequency range tested.. especially in an amp with feedback.
If you've not seen this: Graphs - WIMA – Competence in Capacitors
What is interesting is the 'general' ESR graph that shows the difference between metalised and foil.
What is interesting is the 'general' ESR graph that shows the difference between metalised and foil.
I'm not going to slog through the crapfest so sorry if this has already been pointed out.
A well designed circuit wouldn't be so sensitive to minor changes in component characteristics.
A well designed circuit wouldn't be so sensitive to minor changes in component characteristics.
I for one look forward to the days that such well designed circuits exist. Until and if that time ever eventuates, components will rightly continue to be selected on the basis of having the subjectively best compromise of characteristics for the specific application, as they have since the dawn of audio recording and playback, and in every other field of electronics.
That's true.
However, there are many ways to mitigate the effect of component tolerance in some circuits. Do you know what the tolerance is on individual "components" inside an op amp? It's not 5%, that's for sure. Yet, they provide consistent and predictable performance.
On the other hand, many audio circuits (and other circuits) are dependent on tightly matched, close tolerance components. Example, a filter or crossover circuit; if the parts don't match closely, then the filters won't match from one channel or another; and in the case of a crossover, there will be a "hole" or overlap at the crossover frequency.
For higher order filters, this dependence on high tolerance closely matched components is compounded.
So, for a capacitor bleeder resistor, tolerance matters little. For a series output resistor, it matters more. For a filter, it becomes critical. I stock some resistor values in 2% tolerance, because for what I always use them for it's close enough. Most others are 1%.
However, there are many ways to mitigate the effect of component tolerance in some circuits. Do you know what the tolerance is on individual "components" inside an op amp? It's not 5%, that's for sure. Yet, they provide consistent and predictable performance.
On the other hand, many audio circuits (and other circuits) are dependent on tightly matched, close tolerance components. Example, a filter or crossover circuit; if the parts don't match closely, then the filters won't match from one channel or another; and in the case of a crossover, there will be a "hole" or overlap at the crossover frequency.
For higher order filters, this dependence on high tolerance closely matched components is compounded.
So, for a capacitor bleeder resistor, tolerance matters little. For a series output resistor, it matters more. For a filter, it becomes critical. I stock some resistor values in 2% tolerance, because for what I always use them for it's close enough. Most others are 1%.
Burn in or rather "Reforming" of electrolytic caps is long known in the world of photo flash. If left idle for a long time, the storage caps in a flash will not fully charge, meaning under exposure - at least in older types of flash that didn't have fancy exposure meters. Running them thru a few charge/discharge cycles usually brought them back to full capacity.
I've never heard of anything like this with film caps. Perhaps the audible change came not from the Wimas, but from the PSU caps?
Lots of info about reforming electrolytic caps on the web, here is a nice page with good info. Rap on Replacing Electrolytic Capacitors
I've never heard of anything like this with film caps. Perhaps the audible change came not from the Wimas, but from the PSU caps?
Lots of info about reforming electrolytic caps on the web, here is a nice page with good info. Rap on Replacing Electrolytic Capacitors
Some film caps that use metalised plastic film can self heal the plastic film, essentially melting and sealing any holes. Naturally this isn't going to repatch the metalised layer on top but it reduces through leakage.
Electrolytic caps, I suspect that something similar occurs chemically, I would theorise (without have a read up on the subject) there's probably something chemically going on - perhaps between plate and electrolyte. Also there's probably a residual chemical charge within the electrolyte that's completely 'flat' in the same way that electrolytics self charge up after being discharged.